Sheldon Adelson, one of most-generous Republican contributors, easily stroked a $5 million check to a secretive political committee that's about to air a rare and brutal half-hour documentary trashing Mitt Romney as a corporate raider who's "more ruthless than Wall Street."

But it's nothing personal, say sources familiar with Adelson and the indirect beneficiary of his largesse, Newt Gingrich. The two have known each other for almost 20 years, when the pro-Israel Adelson found a good friend in House Speaker Gingrich.

"This is supporting a friend in an important part of his political career," a source said. "This is nothing against Mitt Romney. He likes Mitt Romney. He will support Mitt Romney if he's the nominee."

But after Restore our Future, the pro-Romney committee, ripped Gingrich apart in Iowa, Adelson was there to help the pro-Gingrich Winning Our Future. Adelson hadn't seen the Winning Our Future ad, nor is it clear if he'll give more money.

"He has made no future obligations," said the source.

That indicates South Carolina might be a last stand, of sorts, for Gingrich. If he doesn't win, donors like Adelson might not help support Winning Our Future, thereby effectively ceding Florida to Romney, who's making a multi-dimensional push here.

But Adelson still might help out more.

"Sheldon Adelson is old-school," said another. "He sticks by his friends."

While $5 million seems like a lot, Adelson is one of the richest men in the country. He's the head of Las Vegas Sands Corp, and began the push last year to bring high-end casinos to Florida. Adelson's such a respected voice in Republican circles that Gov. Rick Scott once made a special stop in Vegas to meet with the donor at the Venetian.

Adelson'sd contribution to Gingrich was a personal donation. It wasn't made on behalf of the company.

Bloomberg got an advanced copy of the documentary and reports:

The film, obtained by Bloomberg News, attacks Romney’s record as the chief executive officer of Bain Capital LLC, a private-equity firm. It highlights the stories of workers who lost their jobs after the companies they worked for were acquired by Bain.

“Make a profit,” a laughing Romney is shown saying in the film. “That’s what it’s all about, right?”

Entitled “When Mitt Romney Came to Town,” the film produced by Jason Killian Meath, a former Republican National Committee aide, is being funded by Winning Our Future, an organization run by longtime aides to Gingrich. Sheldon Adelson, chairman and chief executive officer of Las Vegas Sands Corp. (LVS), and a Gingrich supporter, has given Winning Our Future $5 million to help air the film in South Carolina, which holds its presidential primary election on Jan. 21.

“It’s absolutely brutal in its depiction of the activities of Bain Capital under Governor Romney,” said Stephen K. Bannon, a conservative filmmaker who interviewed Barry Bennett, a supporter of Texas Governor Rick Perry who commissioned the film, on his show at KABC Radio in Los Angeles. ’’But it wouldn’t be an issue except for the fact that Governor Romney’s made it the central part of this thesis for why he should be elected.’’